Selection for resistance to methoxyfenozide and 20-hydroxyecdysone in cells of the beet armyworm, Spodoptera exigua

In this report with an ecdysteroid-responsive cell line of the beet armyworm, Spodoptera exigua (Se4) selection for resistance against methoxyfenozide and the insect moulting hormone (20-hydroxyecdysone, 20E) was carried out to analyze the resulting resistant cells in order to elucidate possible mechanisms of resistance towards these compounds. From these cultures, five methoxyfenozide- and four 20E-resistant subclones were selected starting from 0.1 nM methoxyfenozide up to 100 microM and from 10 nM 20E up to 100 microM, respectively. To date, the selected cells kept their loss of susceptibility for 100 microM. Here we evaluated two processes known to be important in insecticide resistance, namely metabolism and pharmacokinetics, in the selected methoxyfenozide- and 20E-resistant subclones. Synergism experiments with piperonyl butoxide, S,S,S-tributyl phosphorotrithioate, and diethyl maleate, which are respective inhibitors of monooxygenases, esterases, and gluthation-S-transferases, did not affect the level of the resistance. To check the possible existence of active transport in the resistant cells, we used ouabain, an inhibitor of active membrane transport. In parallel, the absorption profile was studied in resistant and susceptible cells with use of 14C-methoxyfenozide. Interestingly, resistant subclones showed cross-resistance towards methoxyfenozide and 20E. The resistance was irreversible even after the compounds were removed from the medium.     

Insights into oncogenic mutations of plexin-B1 based on the solution structure of the Rho GTPase binding domain

The plexin family of transmembrane receptors are important for axon guidance, angiogenesis, but also in cancer. Recently, plexin-B1 somatic missense mutations were found in both primary tumors and metastases of breast and prostate cancers, with several mutations mapping to the Rho GTPase binding domain (RBD) in the cytoplasmic region of the receptor. Here we present the NMR solution structure of this domain, confirming that the protein has both a ubiquitin-like fold and surface features. Oncogenic mutations T1795A and T1802A are located in a loop region, perturb the average structure locally, and have no effect on Rho GTPase binding affinity. Mutations L1815F and L1815P are located at the Rho GTPase binding site and are associated with a complete loss of binding for Rac1 and Rnd1. Both are found to disturb the conformation of the beta3-beta4 sheet and the orientation of surrounding side chains. Our study suggests that the oncogenic behavior of the mutants can be rationalized with reference to the structure of the RBD of plexin-B1.     

Preliminary report on yellow long-tailed macaques (Macaca fascicularis) at Kosumpee Forest Park, Thailand

We conducted a census on long-tailed macaques (Macaca fascicularis) at Kosumpee Forest Park, Thailand, and found 15 individuals of yellow pelage color out of a total of 287 individuals. There were three troops, designated A, B and C, but the yellow macaques were found only in B and C troops. The frequency of yellow macaques was 5.2% in the total population and 4.2 and 9.9% in B and C troops, respectively. These frequencies are much higher than those in rhesus macaques (M. mulatta) reared at Cayo Santiago (0.52%). They are, however, lower than those of 10 years ago.     

Endothelin receptor blockers reduce I/R-induced intestinal mucosal injury: role of blood flow

The aim of the present study was to assess the role of endothelin (ET) in ischemia-reperfusion (I/R)-induced mucosal injury. Mucosal permeability ((51)Cr-EDTA clearance) and tissue myeloperoxidase (MPO) activity were significantly increased after 30 min of ischemia followed by 30 min of reperfusion. The I/R-induced increases in mucosal permeability and polymorphonuclear leukocyte (PMN) infiltration were significantly attenuated by pretreatments with ET(A) (BQ-485) and/or ET(B) (BQ-788) receptor antagonists. Monoclonal antibody (MAb) directed against intercellular adhesion molecule-1 (ICAM-1; MAb 1A29) and superoxide dismutase (SOD) pretreatments significantly attenuated the increased mucosal permeability and PMN infiltration in a similar manner as with ET receptor antagonists. Superior mesenteric artery blood flow was significantly reduced during the reperfusion period. Both ET receptor antagonists caused a significant rise in blood flow compared with an untreated I/R group. In conclusion, our data suggest that ET(A) and/or ET(B) receptors, ICAM-1, and superoxide play an important role in I/R-induced mucosal dysfunction and PMN infiltration. Furthermore, ET is involved in the pathogenesis of post-reperfusion-induced damage and beneficial effects of ET receptor antagonism are related to an improvement of disturbed blood flow during the reperfusion period.     

Acylated flavonol glycosides from leaves of Planchonia grandis

Three acylated flavonol glycosides have been identified from leaves of Planchonia grandis Ridley. They possess kaempferol as aglycone and two triglycosidic chains substituting hydroxyl groups at the 3- and 7-positions. The first glycosidic unit of each chain is esterified by a cis or trans p-coumaric acid. Structural elucidation was achieved by means of UV, NMR and mass spectrometry.     

Atomic-resolution STM structure of DNA and localization of the retinoic acid binding site

Single-molecule imaging by scanning tunnelling microscopy (STM) yields the atomic-resolution (0.6A) structure of individual B-type DNA molecules. The strong correlation between these STM structures and those predicted from the known base sequence indicates that sequencing of single DNA molecules using STM may be feasible. There is excellent agreement between the STM and X-ray structures, but subtle differences exist due to radial distortions. We show that the interactions of other molecules with DNA, their binding configurations, and the structure of these complexes can be studied at the single-molecule level. The anti-cancer drug retinoic acid (RA) binds selectively to the minor groove of DNA with up to 6 RA molecules per DNA turn and with the plane of the RA molecule approximately parallel to the DNA symmetry axis. Similar studies for other drug molecules will be valuable in the a priori evaluation of the effectiveness of anti-cancer drugs.     

The elongated first fibronectin type III domain of collagen XIV is an inducer of quiescence and differentiation in fibroblasts and preadipocytes

Collagen XIV (CXIV) is a fibril-associated collagen that is mainly expressed in well differentiated tissues and in late embryonic development. Because CXIV is almost absent in proliferating and/or dedifferentiated tissues, a functional role in maintaining cell differentiation is suspected. We demonstrate antiproliferative, quiescence- and differentiation-inducing effects of human CXIV and its recombinant fragments on mesenchymal cells. In primary human fibroblasts, in mouse 3T3 fibroblasts and in 3T3-L1 preadipocytes, CXIV reduced de novo DNA synthesis by 75%, whereas cell numbers and viability remained unaltered. Cells showed no signs of apoptosis, and maximal proliferation was restored when serum was supplemented, thus indicating that CXIV induced reversible cellular quiescence. Exposure of fibroblasts to CXIV in vitro led to cellular bundles and clusters. CXIV also triggered trans-differentiation of 3T3-L1 preadipocytes into adipocytes, as could be shown by lipid accumulation and by expression of the glucose transporter Glut4. These effects were also observed with the amino-terminal recombinant fragment Gln(29)-Pro(154) that harbors the first fibronectin type III domain and a 39-amino-acid extension, whereas no activity was found for all other recombinant CXIV fragments. Based on these finding the development of small molecular analogs that modulate fibroblast cell growth and differentiation, e.g. in wound healing and fibrosis, seems feasible.     

Role of education in reducing child labour: evidence from rural Bangladesh

This paper explores the hypothesis that the level of education of children and their parents plays a major role in reducing child labour. Data were generated from a sample survey of 3809 children aged 10-14 years living in 150 villages in two rural districts of Bangladesh. A significant inverse relationship was found between child labour and years of schooling. Age and education of children, parental education, land ownership of household and fathers' occupation were the determinants of child labour force participation. Child's years of schooling is the variable that has most influence on the probability of participation in the labour force, followed by father's and mother's education.